quakeforge/doc/mapformat.txt

//unfortunately, have to wrap the docs in a C comment for doxygen
/**
\page mapformat Map (.map) File Format

"//" marks a comment which extends to the end of the current line

Note that () and {} characters require white space around them.

A map consists of a series of entities delineated by {}

An entity consists of a series of either epairs or brushes, one per "line".

An epair is a pair of quoted (via "quotes") strings. The first string of the
pair is the key, the second string the value. epairs are used to populate the
dictionary of the entity.

A brush is a simple, convex polytope delineated by {}. The format of a brush
is as follows:
\verbatim
{
[optional vertex list]
<plane spec> <texture name> <texcoord spec> [optional flags]
<plane spec> <texture name> <texcoord spec> [optional flags]
<plane spec> <texture name> <texcoord spec> [optional flags]
...
}
\endverbatim
That is, an optional vertex list followed by a number of surface specs, one
per line.

The optional vertex list, found in map files produced by Quest3d, is denoted
by a colon followed by a number indicating the number of vertexes in the list.
Following this, one per line, come the 3d coordinates of the vertexes, one
vertex per line. The vertex coordinates are listed in X Y Z order.

There are two formats for the plane spec, selected via the presence (vertex
mode) or absence (plane point mode) of the vertex list.

In vertex mode, the plane spec directly describes the shape of the surface
polygon. It is simply a number indicating the number of vertexes, followed by a
set of 0 based indexes, enclosed in (). The indexes indicate which of the
vertexes from the vertex list to use. When compiling the map, only the first 3
vertexes are significant: they are used as the 3 points for calculating the
plane.

In point plane mode, the plane spec consists of three point vectors, each
enclosed in ().

The three points (from either mode) are then used to calculate the plane
normal and offset:
\verbatim
n = (p0 - p1) x (p2 - p1) # normal
d = p1 . n # offset
\endverbatim

The texture name is just a simple string (no spaces) that specifies the name
of the texture within the wadfile.

The texcoord spec is black magic. :) It can be either:
(halflife style)
\verbatim
[ sx sy sz s ] [ tx ty tz t ] r s_scale t_scale
\endverbatim
or (quake style)
\verbatim
s t r s_scale t_scale
\endverbatim
In quake style, the basis vectors for s and t (sv and tv) are taken as the
most appropriate axial plane for the surface plane. In halflife style, they're
given directly via sv = (sx sy sz), tv = (tx ty tz). sv and tv are then
transformed by rotating around their perpendicular by r degrees. How this
interacts with halflife style is currently unknown. When rendering, the texture
coords (rs, rt) for vertex v are calculated as:
\verbatim
rs = v . sv + s
rt = v . tv + t
\endverbatim

The optional flags indicate various options for the surface. So far, the only
flag supported is "detail", indicating that the brush is a detail brush and not
to be used for visibility calculations. If any surface has the detail flag set,
the whole brush is affected.

Example map file (vertex mode):
\verbinclude cliptest.map
*/